Can I use Substittoad efffect on Poison Draw Frog to special summon another Poison Draw Frog and draw 1 card for the previous Poison Draw Frog that was sent to grave?

No, because Poison draw frog misses the timing.

Poison Draw Frog is an optional effect due to the "you can" part of his text. In the case of optional effects, the last thing to happen has to be the same thing that sets off that effect. In the case of Poison Draw Frog (and Dupe Frog) being tributed for Substitoad's effect, the last thing to happen is Substitoad summoning a monster to the field, not Poison Draw Frog (or Dupe Frog) being sent to the graveyard. That is why they miss the timing.

Locked.